The PID test was conducted by TUV SUD to assess loss of power output of solar modules under severe conditions of high voltage, high temperature and high humidity. ReneSola's 300 W multicrystalline solar module was exposed to 1,000 V of bias voltage at a temperature of 85 degrees C and a relative humidity of 85% for 96 consecutive hours.

During the test, ReneSola's maximum degradation of power output was 1.34%, significantly below the maximum allowable power output degradation of 5%, the company says.